Due to the popularity of social media, e.g., TWITTER®, many companies set-up official accounts to provide online customer service. Unlike a conventional telephone call, customers and agents interact asynchronously via the web, e.g., publish tweets and ‘@’ the particular account. While there is more convenience, customers tend to be quite emotional via an online help desk. Besides providing a correct solution for the problem, it is equally important for online customer agents to properly pacify emotions.